Diluted phosphoric acid in the form of a viscous liquid is commonly used by dentists to help clean an opening in a tooth to be filled with a restorative material. Diluted phosphoric acid has commonly been dispensed through a conventional syringe. Any one application of the diluted phosphoric acid to a tooth requires only a small portion of the diluted phosphoric acid typically held by such a syringe, however, and between applications the diluted phosphoric acid has a tendency to solidify in the nozzle of the syringe due to exposure of the diluted phosphoric acid to the atmosphere thorough the outlet opening of the syringe. This solidified diluted phosphoric acid then forms a plug which must be expelled before the non-hardened diluted phosphoric acid can be expelled. Such expulsion of the plug of solidified diluted phosphoric acid is typically done by manually applying pressure against the plunger of the syringe, which pressure is hard to stop at the instant the plug is discharged s that a large unwanted amount of the liquid diluted phosphoric acid can also be discharged onto a patient's clothes or skin, or into the patient's mouth, which can result in damage or injury.